1. Technical Field
The present invention relates to a vibration isolator for supporting a load and preventing transmission of vibration between one member of a vibration generating section and a vibration receiving section and the other member of the vibration generating section and the vibration receiving section, and to a method for mounting the same.
2. Related Art
Lightweight trucks and some passenger cars have a body provided with a lower traveling body and a cabin (cab), i.e., a driver's room, mounted thereon. In such weight trucks, the cab is mounted on the body through an intermediary of a vibration isolator having a vibration isolating function so that vibration caused during operation and traveling can not be transmitted from the body to the cab.
One described in Japanese Patent Application Laid-Open No. H6-50135 (Patent Literature 1) has been known as a vibration isolator used for the use described above. The vibration isolator described in Patent Literature 1 has a cylindrical body (outer tube) whose one end is closed, an inner tube disposed inside of the outer tube, an elastic body (rubber-like elastic body) attached to the outer tube to suppress a displacement in a radial direction of the inner tube that penetrates movably in an axial direction with respect to the outer tube, damper solution stored in a liquid chamber within the outer tube and a damper member fixed to an lower end of the inner tube and is soaked into the damping fluid.
In the weight truck and the like described in Patent Literature 1, the body is provided with a mounting hole formed so as to penetrate through in the axial direction and the vibration isolator is fixed on the body through a plurality of flanges extending from the lower end of the outer tube to an outer peripheral side while inserting a lower part of the vibration isolator (a lid part formed by closing the lower end of the outer tube) into the mounting hole. The vibration isolator is also provided with a plate that is fixed to an upper end of the inner tube and that creates an air chamber between the outer tube is fastened and fixed to the cab. Thereby, the vibration isolator of the Patent Literature 1 supports an inputted load by spring reaction force of an air spring, and it blocks and damps vibrations by the spring reaction force of the air spring and by viscous resistance that is applied to the damping member from the damping fluid.
There has been also known an apparatus provided integrally with a dynamic damper as a vibration isolator as described in Japanese Patent Application Laid-Open No. 2002-147530 (Patent Literature 2). The vibration isolator described in Patent Literature 2 is constructed as a so-called bush type and has an inner tube, an outer tube elastically connected to the inner tube through an intermediary of a rubber-lie elastic member, a mass disposed on an outer peripheral side of the outer tube and an elastic connector for elastically connecting the mass with the outer tube. It is possible to efficiently reduce a total manufacturing cost by integrally constructing the vibration isolator and the dynamic damper as the vibration isolator described in Patent Literature 2.
One described in Japanese Patent Application Laid-Open No. H10-267084 (Patent Literature 3) has been also known as a vibration isolator provided with a dynamic damper.
By the way, when the vibration isolator is integrated with the dynamic damper, it is necessary to connect the dynamic damper (the elastic connector and the mass) to the other end of the inner tube to reduce resonance vibration of the cab when one end of the inner tube is connected to the cab as the vibration isolator described in Patent Literature 1. However, it is difficult to connect the dynamic damper to the inner tube while avoiding interference with the outer tube, the body and fastening members such as a bolt in the vibration isolator as described in Patent Literature 1.
Then, the vibration isolator is disposed normally between the body and the cab and the dynamic damper is assembled separately to the cab to reduce the vibration in the weight trucks and the like using the vibration isolator as described in Patent Literature 1. Therefore, works for assembling the vibration isolator and the dynamic damper respectively to the weight trucks and the like have been required, increasing a number of their assembling steps, and it has been difficult to reduce the total manufacturing cost.
Accordingly, in view of the facts described above, it is an object of the invention to provide a vibration isolator, and its mounting method, in which a dynamic damper containing a mass and an elastic connector is connected to an inner tube so as to be able to provide the dynamic damper as a part of the apparatus.